<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>2_变量与常量</title>
</head>
<body>
<script>
    var a=10;
    a=6.6;
    a=false;
    console.log(a);
    var a='呵呵呵呵呵呵';
    console.log(a);

    //4.let关键字声明变量
    let x=1;
    x=6.6;
    console.log(x);
    //使用let重复声明会报错

    //const声明常量
    const y=1;
    console.log(y);
    //常量值不允许被修改 报错



</script>
</body>
</html>